Have you seen pictures of ocean waves, waterfalls or streams with silky effects? It’s not tough and something you can learn very quickly. All you need is the right camera settings and steady hands.
Remember to balance light in your camera. You want a slow shutter speed but you also don’t want too much light so you would need to keep your aperture and your ISO low.
With a fairly slow shutter speed you would either need to take a tripod or keep your camera really steady. It’s not possible to carry your tripod everywhere so find a rock or a steady base and leave your camera there.
And finally, be careful of your surroundings for slippery rocks or too much water stream entering your lenses. Use a polariser to control light.